Pneumatic time delay switch with improved auxiliary manual switch actuator means

ABSTRACT

An electrical switch includes a pneumatic time delay mechanism to provide a delay between release of the actuator and return of the contacts to their initial condition. A pivoted lever member associated with the actuator energizes the pneumatic mechanism and initiates the delay function upon release of the actuator.

United States Patent Inventor Appl. No.

Filed Patented Assignee John J. Dennison Southington, Conn. 827,363

May 23, 1969 June 15, I971 Arrow-Hart, Inc. Hartford, Conn.

PNEUMATIC TIME DELAY SWITCH WITH IMPROVED AUXILIARY MANUAL SWITCH ACTUATOR MEANS 4 Claims, 4 Drawing Figs.

Int. Cl. H0lh 7/03 Field of Search References Cited UNITED STATES PATENTS Ballou Priesemuth Frisk Bauer Willcox Primary Examiner-J. R. Scott Attorney-Davis, Hoxie, Faithful] and Hapgood ABSTRACT: An electrical switch includes a pneumatic time delay mechanism to provide a delay between release of the actuator and return of the contacts to their initial condition. A pivoted lever member associated with the actuator energizes the pneumatic mechanism and initiates the delay function upon release of the actuator.

P UMA Ic T ME L SWITC W TH MR YE AUXILIARY MANUAL swrrcn ACTUATOR ME ns The present invention is concerned with a switch which pneumatically provides an adjustable delay between release of the actuator and movement of the contacts. The switch contacts can be arranged to make contact, break contact, or change to a secondicontact after the delay. The switchassembly is useful for motor starting where windings are connected in a time sequence. It also canbetlsed to establish a minimum recycle time for such applications as refrigeration compressors. i i v According to the present invention, release of an actuator frees a spring loaded bellows to expand at a rate determined by an adjustable air outlet flow control. The expanding bellows cause the switch contacts to change their position to accomplish the switching fnnction. In the drawings:

FIG. 1 is an elevational view partially in section of a switch according to the present invention; l i v FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a perspective detail of the actuator'and lever members; and v r A I v 5' FIG. 4 is a sectional view taken along line of FIG. 1

Referring now to the drawings, particularly FIG. 1, the switch mechanism of the present invention is housed in a three part case comprising a lower portion 10, an intermediate por tion 11, and an upper portion 12. The housing portions are assembled with screws. Lower portion 19 includes a pair of moving contact blade members 13 associated with a spring 14 whichprovides toggle action to bias the moving contact blade members 13 upwardly or downwardly against fixed contacts in a conventional manner. F contact members 16 and 18 are afiixed to the lower portion such that the moving contact blade members can establish spring-biased contact with the fixed contacts. In the switch assembly illustrated in FIG. 1, the normal condition completes the circuit with fixed contacts 1. A vertically reciprocable blade carrier l9fhaying blade receiving grooves is located between the pair of contact blade members 13 such that upward motion of the blade carrier 19 from the position illustrated in FIG. 1 will cause the contact blade members 13 to snap over to establish contact with fixed contacts 16. A spring 23 biases blade carrier 19 upwardly.

Intermediate honsing portion I1 includes a bellows member 20 which is formed of elastomeric material. Within bellows 20 is an actuator spring 22 which acts downwardly against a disc member 24 affixed to or integral with a plunger. Spring 22 tends to urge the plunger downwardly to extend the bellows and to cause actuation of the switch contacts. Spring 22 has a spring rate great enough to overcome the bias of spring 23. Another spring 28 bears against an annular washer member 27 associated with the plunger Spring 28 is'arranged to bias a movable annular washer member upwardly of the plunger 26 against the lower edge portion 21 of the bellows member 29 to urge the bellows 'edge 21 against the disc 24 to form therewith acheclt valve.

The upper housing portion -12 includes an air inlet plug valve member 30 having a tapered plug portion 31 and having a portion 32 in threaded association with an insert member 33 affixed in upper housing portion 12 to permit vertical position adjustment of the tapered portion 31. The vertical adjustability of plug valve member 3!) permits a variable clearance between the tapered portion 31 and the bore 34 into whichit fits. This clearar ce provides an air inlet orifice of variable dimension leading to the interior of the bellows member A pad of filter material 38 such as polyurethane foam is included in the upper housing portion 12 and serves to clean the air before it enters the clearanee space about the tapered portion 31 of valve member Adjustment of plug valve 30 is accomplished by a screwdriver, slot 35 in the protruding threaded portion 32. A cover36 may be provided to discourage tampering with the adjustment and for protection. t

. ing the contact transfer to fixed contacts 16.

As is best illustrated in FIG. 2, he switch mechanism is actuated by an actuator member dojjha n41 which protrudes from an appropriate op ing in l er housing portion 10 to be engageable an external dev e. Actuator member 40 is a rod vertically reciprocable within a vertical bore in the housing and is biased upwardly by a spring 42..As is best seen in FIG. 3, actuato'rportion is located ina slot in a bifurcated lever member tit) which comprises a pair of similar lever members 61, 62 integrally joinedl Actuator 40 includes a portion 45 transverse toportion'di. transverse portion overlies the proximal. ends. of the lever pair so that downward force on the actuator will be transmitted to the proximal ends. Lever 60 is pivoted with respect to the housing by a trunnion 6 3. The distal ends film] a yoke about a plunger 26 and are arranged to bea against annolar washer 2 7 whieh is fixed to plu nger 26. Downward rnotion of actuator 41) thus results inupward motion of plonger t v Operation of the device will now be described. The device is wired in series with a relay coil and physically associated the relay such that the actuator {10 isdepressed so by the relay until the relay is deenergiaed whereupon the delay function of the device prevents reenergizing the relay coil until elapse of the delay interval. Downward movement of the actuator 40 causes ledge of the actuator to engage pro:- jection 17 of the contact blade carrier 19 to secure maintenance of the initial contact condition whereincontact with fixed contacts 18 prevails. i v

When actuator 40 moves downwardly against spring 42, transverse portion 45 bears against the proximal ends oflever member 60 causing it to pivot about trunnion 63. The distal ends of lever member o0 engage the fixed annular washer member 27 to cause upward movement of plunger 26 to collapse bellows 20 and to compress spring y Air within bellows 20 is compressed as the bellows is col lapsed. The resulting superatmospheric pressure deflects bellows edge 21 downwardly against spring-biased washer 29 Deflection of edge creates a passage for compressed air to p bct n'p g r' 26 an he rqu'ndins bcl vt edge 21. Edge 21, washer spring 28, and the surface of plunger cooperate to form a check valve whichrelieves superatmospheric pressure with the bellows during collapsebut seals againstingress of air when the bellows interior subatmos'pheric during extension. i t A v v v V i Release of the actuator initiates the delay function. Spring 42 moves actuator 40 upwardly Ledge no longer blade carrier down. Spring urges blade carrier upwardly causing contact blades l3to through ahori zontal posi tion. In so doing, blade spring 14 is stre ht Spring provides an overcentering toggle" action" which causes the blades 13 to snap downwardly against fixed contacts 16 accomplish Simt ltaneous with actuator release; lever member 60 is released thereby freeing the-collapsed so that they may expand. The checkvalve constituted by bellows edge 21, annular washer and spring closes during extensionof the bellows due to the subatmospheric pressure in the bellows. The w at w s the allot was is shed. y th a s at which air is permitted to enter the bellows through the adjustable orifice whose dimensions are determined by the adjustment ot inlet air valve 39. Air traversing the clearance between tapered plug portion 31 andbore 34 enters bellows 20 relieving the subatmospheric pressure at a rate determined by the setting of air inlet valve 30..

Downward expansion of bellows 20 under the urging of From the above it is apparent that the switch transfers contacts immediately upon release of the actuator and will maintain the contacts in the transferred position until elapse of the Y Because switch devices are frequently employed in unclean environments, applicant provides filter means 38 which may be polyurethane foam pads to clean the air prior to its passage through the adjustable inlet valve orifice. To further promote cleanliness, the air used in the pneumatic system recirculates within the system. This permits hermetic enclosure of the moving parts of the switch if desired. Where hermetic sealing is not necessary, recirculation of air obviates the need to introduce unclear external air to the interior of the device. The path of air circulation is illustrated in FIG. 1 by arrows. Air travels past adjustable plug valve 30 into the bellows interior. Upon release of the actuator, air exits from the bellows by passing through an aperture in disc 24 and then passing between edge 21 and plunger 26. The air is drawn from the interior of the housing through a passage and through filter 38 while the bellows are extending.

The above-described device provides a pneumatic time delay switch having a repeatable time delay of great accuracy. The delay is adjustable over a wide range of times. By recirculating and filtering the air used by the pneumatic system, the device is insensitive to the cleanliness of its environment. The arrangement of the moving contact blades provides rapid and positive contact establishment and maintains adequate contact pressure with: the resulting benefits and reduced arcing, contact sticking, and insensitivity to shock and vibration.

I claim:

1. An adjustable delay time electrical switch having first and second positions, electrical contacts movable between the first position and the second position, fixed contact means engageable by said movable contacts in at least one of said positions, a movable actuator for holding said movable contacts in the first position when actuated, biasingmeans for moving the movable contacts to the second position upon release of the actuator, and a pneumatic time delay device for effecting return of the movable contacts to the first position upon elapse of a delay time after release of the actuator, said time delay device comprising a bellows arranged to be collapsed when the actuator is actuated and spring biased to extend upon actuator release, said bellows being associated with the movable contacts by means of a'reciprocable plunger member which effects the return of the movable contacts from the second to the first position upon extension, an adjustable air orifice to admit air to the interior of the bellows during their extension, the rate of air admission being determinative of the delay time, and a check valve for exhausting the air from the bellows during their collapse during actuation.

2. The switch of claim 1 wherein the actuator is reciprocable and is spring biased against the direction of actuating force and wherein the bellows is collapsed during actuation by means of a pivoted lever member engageable at its proximal end with said actuator and at its distal end with said reciprocable plunger. 7

3. The switch of claim 2 wherein the distal end of said lever member is bifurcated so as to encompass said plunger.

4. The switch of claim 3 wherein the proximal end of said lever is bifurcated, a portion of said actuator is interposed between the bifurcated proximal end portions and said interposed actuator portion is surmounted by a transverse actuator portion such that actuating force on the actuator is transmitted to the bifurcated proximal end portions of the lever. 

1. An adjustable delay time electrical switch having first and second positions, electrical contacts movable between the first position and the second position, fixed contact means engageable by said movable contacts in at least one of said positions, a movable actuator for holding said movable contacts in the first position when actuated, biasing means for moving the movable contacts to the second position upon release of the actuator, and a pneumatic time delay device for effecting return of the movable contacts to the first position upon elapse of a delay time after release of the actuator, said time delay device comprising a bellows arranged to be collapsed when the actuator is actuated and spring biased to extend upon actuator release, said bellows being associated with the movable contacts by means of a reciprocable plunger member which effects the return of the movable contacts from the second to the first position upon extension, an adjustable air orifice to admit air to the interior of the bellows during their extension, the rate of air admission being determinative of the delay time, and a check valve for exhausting the air from the bellows during their collapse during actuation.
 2. The switch of claim 1 wherein the actuator is reciprocable and is spring biased against the direction of actuating force and wherein the bellows is collapsed during actuation by means of a pivoted lever member engageable at its proximal end with said actuator and at its distal end with said reciprocable plunger.
 3. The switch of claim 2 wherein the distal end of said lever member is bifurcated so as to encompass said plunger.
 4. The switch of claim 3 wherein the proximal end of said lever is bifurcated, a portion of said actuator is interposed between the bifurcated proximal end portions and said interposed actuator portion is surmounted by a transverse actuator portion such that actuating force on the actuator is transmitted to the bifurcated proximal end portions of the lever. 